The present invention is directed to a dental patient chair which contains a base part on which an upper chair part comprising a seat, backrest and headrest for the patient is height-adjustably and longitudinally displaceably mounted. The dental patient chair includes an adjustment arrangement having controllable drives by which the height adjustment and longitudinal displacement of the upper chair part relative to the base can be accomplished and further includes additional adjustment devices for adjusting at least the headrest part and the backrest part.
In dental patient chairs, it is known to vary the bearing parts, such as the seat, backrest and head support, in accordance with the required treatment positions with the assistance of suitable adjustable means that can be of a mechanical, electromechanical or hydraulic type. On the basis of such an adjustment, the position, both relative to one another as well as relative to a stationary reference plane such as a wall, floor or chair base, can be varied.
It is also known to define standard treatment positions by control programs, wherein the control programs can be fashioned both fixed, as well as individually variable. Usually, a modern patient chair is currently equipped with three control programs that can be activated or used, as needed, by pressing keys.
Although it is a relief for the treating person, who may be either a physician and/or an assistant, to obtain the different treatment positions in a relatively simple manner by pressing a key and to, thus, be able to set them, it is nonetheless inconvenient for the treating person that, when, for example, the sloping position of the backrest and/or the headrest or head support must be changed during a treatment, the chair must, again, be readjusted to the position previously set to the optimum work attitude. Given such a change in the treatment position, namely the "mouth point", of the patient necessarily changes and results that a correction of the position of the treating person and/or his equipment, such as instrument holders, trays, etc., become necessary for the purpose of adapting to the modified treatment position. The term "mouth point", used hereinabove and hereinafter, is a reference point which is definable in the region of the preparation location of the patient's mouth in relationship to both a horizontal and to a vertical reference plane.
The same is also true given a change of patients, because the treatment position set once for optimum working conditions for one patient is no longer optimally suited, given another patient who usually has a different physical size. Therefore, the position must be corrected.